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Key Terms:
Acquired Immune Deficiency Syndrome (AIDS): arises from depletion of Th cells and as a
result of infection with HIV
Adaptive Immunity: a set of specific mechanisms that respond to specific pathogens; they
develop slower that innate responses but are long lasting; recognizes specific
antigens, responds to an enormous diversity of antigenic determinants,
distinguishes self from non-self, and remembers the antigens it has encountered
setting the organism for prolonged immunity; involves antibody proteins
Allergic reaction: a normally harmless nonself molecule binds to a mast cell causing the
release of histamine and inflammation; the nonself molecule comes from the
environment; triggers an inappropriately strong response to the nonself molecule
Antibodies: part of our body (not the pathogen); reacts to an antigen with antigenic
determinants; proteins that bind specifically to substances identified by the immune
system as nonself. The binding can inactive and destroy microorganisms and toxins,
or tag substances as nonself cells so the immune system can catch them later
Antigen-presenting cell: a cell that ingests and digests an antigen and then exposes
fragments of that antigen to the outside of the cell, bound to proteins in the cell’s
plasma membrane; B cells?
Antigenic determinants: epitopes; body’s response to an antigen with the antibodies; allow
antibodies to match up and attach to an antigen (shape specific).
Antigen: any substance that stimulates the production of an antibody in the body of a
vertebrate
Autoimmune diseases: the immune system fails to distinguish between self and nonself and
attacks tissues in the organisms own body
Autoimmunity: an immune response by an organism to its own cells
Cellular immune response: mediated by T cells; acquires specific receptors to respond to
each antigen
Class I MHC: found on surfaces of most cells in mammals
Class II MHC: found on most immune system cells
Clonal Deletion: inactivation or destruction of lymphocyte clones that would produce
immune rx against the animal’s own body; prevention of autoimmunity
Clonal Selection: accounts for the specificity and diversity of the adaptive immune response
and for immunological memory
Compliment System: more than 20 different proteins in the blood; once this system has
been activated, the proteins function in a characteristic sequence (cascade) with
each protein activating the next step.
Constant Region: determine which of 5 classes the immunoglobulin belongs to (these
classes differ in function and type of heavy chain.)
Cytokines: Soluble signaling proteins released by many cell types; bind to surface cell
receptors and alter the behavior of target cells; can activate or inactivate B cells,
macrophages, and T cells
Cytotoxic T (Tc) cells: recognize and kill virus-infected cells or mutated cells
Defensins: also made my mucus membranes, these are peptides of 18-45 aa; they contain
hydrophobic domains and are toxic to many pathogens; they insert themselves into
the plasma membrane of organisms and make the membranes freely permeable to
water and solutes (way to kill invaders). Defensins also are produced within
phagocytes to kill pathogens consumed by phagocytosis
Effector cells: B cells and T cells that attack an antigen, either by secreting antibodies that
bind to the antigen or by releasing molecules that destroy any cell bearing the
antigen
Histamine: increases the permeability of blood vessels to aid in inflammation; an amino
acid derivative
Human immunodeficiency virus (HIV):
Humoral immune response: part of adaptive immunity; involves antibody production by B
cells (activated by binding of the antigen and by stimulation from Th cells with the
same specificity; they then form plasma cells); acquires specific receptors to
respond to each antigen
Immunity: two possible mechanisms in the body; immunity is the ability to avoid disease
when invaded by a pathogen
Immunoglobulin: made of tetramers of 4 polypeptides; there are 2 identical light chains,
and 2 identical heavy chains, each with a constant region and a variable region;
many protein possibilities result when B cell genomes undergo recombination
events
Immunological memory: part of the clonal selection response; the capacity to more rapidly
and massively respond to a second exposure to an antigen than occurred on first
exposure
Inflammation: a response that activates cells to act against invading pathogens when tissue
is damaged; consists of redness, swelling, and heat which can be painful
Innate Immunity: a set of nonspecific, inherited mechanisms that protect the body from
many kinds of pathogens; first defense is skin barriers and toxic molecules that
destroy invaders; second defense is phagocytes
Interferon: increase resistance of neighboring cells to infection esp from viruses; type of
cytokines
Lymphocytes: WBC; includes B cells and T cells; part of adaptive immunity
Lysozyme: enzyme made by mucus membranes which cleaves the bonds in the cell walls of
bacteria causing them to lyse (burst open)
Major Histocompatibility Complex (MHC): these genes encode membrane proteins that
bind antigenic fragments and present them to the Th cells; 2 classes; important slefidentifying labels that play a role in coordinating interactions between lymphocytes
and macrophages
Mast cells: release histamine, which increases the permeability of blood vessels to aid in
inflammation; adhere to skin and organ linings to release chemical signals
Memory cells: long-lived lymphocytes produced after exposure to antigen. They persist in
the body and are able to mount a rapid response to subsequent exposures to the
antigen
Mucus: slippery secretion produced by the mucus membrane in various body cavities,
which are exposed to the external environment; mucus traps microorganisms so
they can be removed by the beating of cilia which move mucus and trapped debris
out of the body
Natural killer cells: defense cells that circulate the body and work to eliminate invaders by
identifying healthy body cells from infected ones; can initiate apoptosis in infected
cells; these also kill off antigens that have been labeled as targets by antibodies
Pathogens: harmful organisms and viruses that can cause disease
Phagocytes: WBC; defense cells that circulate the body and work to eliminate invaders
through phagocytosis
Plasma cells: formed from B cells; they synthesize and secrete specific antibodies
Primary immune response: the first response of the immune system to an antigen,
involving recognition by lymphocytes and the production of effector cells (T and B
cells) and memory cells
Prostaglandins: fatty acid derivatives that play roles in various responses like the initiation
of inflammation in nearby tissues
Regulatory T-cells (tregs): inhibit the other types of T cells from mounting an immune
response to self-antigens
Secondary immune response: a rapid and intense response to a second or subsequent
exposure to an antigen; initiated by memory cells
Sepsis: generalized inflammation caused by bacterial infection; can cause a dangerous drop
in blood pressure
T-cell receptors: integral membrane proteins on the surfaces of T cells; recognize and bind
to nonself substances presented y MHC proteins on the surface of other cells
T-helper cell (Th): direct cellular and humoral immune responses
Tumor necrosis factor: a cytokine protein that kills target cells and activates immune cells
Vaccination: injection of a virus or bacteria or their proteins into the body to induce
immunity; the injected material is usually attenuated (weakened) before injection
and is called a vaccine
Variable region: determines the specificity of an immunoglobulin
White Blood cells: specialized for various functions in the immune system; 2 major types:
lymphocytes and phagocytes; aka leukocyte
NOTE: QUESTIONS ARE ANSWERED IN PACKET.